CN101235264A - A kind of aqueous polyurethane adhesive and preparation method thereof - Google Patents

Abstract

A water-based polyurethane adhesive and a preparation method thereof, relating to a water-based polyurethane adhesive and a preparation method thereof. The invention provides a water-based adhesive characterized by good adhesion to various substrates, easy coating and high bonding strength and a preparation method thereof. The adhesive is a hydrophilic urethane preform containing self-emulsifying isocyanate end groups produced by the reaction of polyester polyols, diisocyanates, and hydrophilic monomers, and then neutralized, dispersed and emulsified, and chain extended. The prepared polyurethane water-based dispersion is a characteristic water-based polyurethane adhesive.

Description

A kind of aqueous polyurethane adhesive and preparation method thereof

technical field

The invention relates to a water-based polyurethane adhesive and a preparation method thereof.

Background technique

Water-based polyurethane was first prepared by the famous scientist P. Schlack in 1942 by forcing dispersion with an external emulsifier. The self-emulsifying water-based polyurethane successfully developed in 1975 greatly improved the performance. In the 1970s, theoretical research reports on the stability mechanism, phase transition process, structure and performance relationship of waterborne polyurethane began to appear. In the late 1990s, due to environmental protection requirements such as IS014000 and green chemical industry, the development of water-based polyurethane reached a climax. So far, there are more than 800 related patents.

U.S. Patent No. 3,036,998, 3,756,992 once reported the preparation method of polyurethane aqueous dispersion. Japanese Patent Publication No. 61-35212 reports a method for preparing an aqueous polyurethane dispersion characterized by mixing a hydrophilic carbamate containing an oxirane group and a hydrophilic carbamate. However, the proportion of oxirane groups in the hydrophilic urethane in this patent is as high as 40-98%, and the water-resistant peeling degree of the adhesive after processing is significantly reduced, which cannot meet the water resistance and high viscosity of the water-based adhesive. Requirements for bonding strength. Also, JP-A-2-20511 reports a method for preparing an aqueous polyurethane dispersion characterized by emulsifying and dispersing a self-dispersing water-based polyurethane that is essentially a water-insoluble isocyanate-terminated carbamate. However, most of the water-soluble polyurethanes used in this patent are used as hydrophilic groups. Due to hydrolysis, the molecular weight is obviously reduced, and there is a problem that the stability of the particles decreases. JP-A 7-157527 reports a preparation method in which a tackifier is mixed with an aqueous carbamate. It is pointed out in this patent that due to the addition of the tackifier, the adhesion to the olefin substrate is improved. Generally, due to the addition of the tackifier, the viscosity of the resin is reduced, and the adhesion to the substrate is improved. Therefore, it is difficult to find Optimum balance of viscosity and heat resistance.

Contents of the invention

具备优良粘接性，特别是在50～70℃的低温条件下干燥后粘贴，也显示出高的粘接强度和加工后具有优异耐热性为特征的水性聚氨酯胶粘剂制备方法。The object of the present invention is to provide a kind of easy coating to various substrates,

It has excellent adhesiveness, especially after drying at a low temperature of 50-70°C, it also shows high adhesive strength and excellent heat resistance after processing. It is a water-based polyurethane adhesive preparation method.

The present invention includes following technical solutions:

1. A water-based polyurethane adhesive is prepared according to the following steps: heat the mixture of polyester polyol and hydrophilic monomer to 100-120°C, after vacuum dehydration, pass through _N2 to cool to 60°C, add diisocyanate and tin The catalyst is reacted at 50-90 DEG C for 1-3 hours to prepare a polyurethane prepolymer containing hydrophilic isocyanate end groups. Add organic solvent and small molecule chain extender to carry out chain extension reaction at 50-90°C for 1-10 hours, cool to 40-50°C, add alkaline aqueous solution to neutralize and disperse under vigorous stirring, and finally vacuum desolventize to obtain water-based polyurethane Dispersions.

2. water-based polyurethane adhesive as described in item 1, the polyester polyol of the polyurethane prepolymer that prepares the isocyanate terminal group that contains hydrophilic group can be by polyadipate-1,4-butylene glycol, polyethylene adipate Diol, polyethylene adipate-propylene glycol, polyethylene adipate-diethylene glycol, polyethylene adipate-diethylene glycol, polyethylene adipate-1,4- Optional one or two of butanediol.

3. the water-based polyurethane adhesive as described in item 1, the diisocyanate of the polyurethane prepolymer that prepares the isocyanate terminal group that contains hydrophilic group can be by toluene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexa Methylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- or 1,4-diisocyanate, isophorone diisocyanate, diphenylmethane 4,4-di Isocyanate, dicyclohexylmethane diisocyanate, 1,6-hexanediisocyanate, xylylene diisocyanate, naphthalene-1,5-diisocyanate, methylcyclohexyl diisocyanate, tetramethylxylylene diisocyanate Choose one or both.

4. As the water-based polyurethane adhesive described in item 1, the hydrophilic monomer of the polyurethane prepolymer containing the isocyanate terminal group of the hydrophilic group can be prepared by 2,2`-dimethylol propionic acid, 2,2`-di Optional one or two of hydroxymethylbutyric acid, 2,2'-dimethylolvaleric acid, and 2,2'-dimethylol octanoic acid.

5. The water-based polyurethane adhesive as described in Item 1, the reaction temperature for forming the polyurethane prepolymer containing isocyanate terminal groups of hydrophilic groups is 70-80°C.

6. The water-based polyurethane adhesive as described in item 1, the temperature of the chain extension reaction is 60-70°C.

7. The water-based polyurethane adhesive as described in item 1, the time of the chain extension reaction is 2-3 hours.

8. The water-based polyurethane adhesive as described in item 1, the organic solvent is acetone, butanone, N-methylpyrrolidone, ethyl acetate, dimethylformamide or a mixture.

9. The water-based polyurethane adhesive as described in item 1, the small molecule chain extender is ethylene glycol, butylene glycol, hexanediol, diethylene glycol, neopentyl glycol, trimethylol propane, ethylenediamine, One or a mixture of melamine, 1,4-butanediamine, and propylenediamine.

10. The water-based polyurethane adhesive as described in item 1, the alkaline substance in the alkaline aqueous solution is NaOH, KOH, triethylamine, trimethylamine.

11. The water-based polyurethane adhesive as described in item 1, the tin catalyst is dibutyltin dilaurate, stannous octoate.

The reaction process of the present invention is as follows:

The water-based polyurethane adhesive of the present invention can be used as after being appropriately modified: (1) wood processing adhesive: an adhesive used for plywood, fiberboard, particle board, etc. (2) Adhesives for shoes. (3) Fabric and flocking: used to make high-quality composite fabrics, non-woven fabrics, and carpets. (4) Bonding processing of various substrates: used for bonding or bonding plastic sheets or films such as PVC, PET, PP, ABS, PE, fabric (cotton or chemical fiber), non-woven fabric, paper, glass, etc. processing. (5) Coating agents: leather coatings, fabric coatings, fiber treatment agents, decorative coatings, primers, etc. It can be widely used in shoemaking, construction, instrumentation, automobile decoration material components and the like.

The present invention adopts polyester polyol, polyether polyol, polycarbonate polyol as the representative of high molecular weight polyol, and these high molecular weight polyols can be used alone or in combination, and their copolymers can also be used, Considering the adhesion to a wide range of substrates and the price, polyester polyol is used as the main body.

The above-mentioned polyester polyol is made of polyadipate-1,4-butylene glycol, polyethylene adipate (PEA), polyethylene adipate-propylene glycol, polyadipate-diethylene Diol (PDA), polyethylene adipate-diethylene glycol, polyethylene adipate-1,4-butanediol is optional one or both.

When the present invention prepares polyurethane aqueous dispersion, the organic polyisocyanate of use is the compound shown in formula [1] R (NCO) _n (R in the formula is any divalent organic group, n >= 2), has: toluene di Isocyanate (TDI), 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- Or 1,4-diisocyanate, isophorone diisocyanate (IPDI), diphenylmethane 4,4-diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), 1,6-hexamethylene diisocyanate (HDI ), polymethylene polyphenyl isocyanate (PAPI), xylylene diisocyanate (XDI), naphthalene-1,5-diisocyanate (NDI), methylcyclohexyl diisocyanate (HTDI), tetramethyl xylylene diisocyanate (TMXDI), etc. In particular, it is desirable to use an aromatic hydrocarbon diisocyanate compound from the viewpoint of mechanical strength. On the other hand, it is desirable to use an aliphatic hydrocarbon or alicyclic hydrocarbon diisocyanate compound from the viewpoint of durability and light resistance.

The content rate of isocyanate in the final solid component of water-based polyurethane is preferably 8-30%. In this range, the adhesive force of urethane is suitable and high adhesive strength can be obtained.

The present invention preferably adopts strong hydrophilic water-soluble anion groups such as carboxylic acid group, sulfonic acid group, or carboxylic acid group and sulfonic acid group as the hydrophilic group of water dispersibility (hydrophilicity) in polyurethane. The solid content of carboxylic acid groups, sulfonic acid groups, or hydrophilic groups such as carboxylic acid groups and sulfonic acid groups in the hydrophilic polyurethane is preferably 50 to 1000mmol/kg of the solid content of polyurethane, within this range, It does not impair the water resistance, but also maintains the stability of the particles, because the water dispersibility of polyurethane has a strong correlation with the particle size.

Representatives of polyols containing carboxylic acid groups are: 2,2`-dimethylolpropionic acid, 2,2`-dimethylolbutyric acid, 2,2`-dimethylolvaleric acid, 2,2 `-Dihydroxymethyl octanoic acid etc. When these are synthesized into polyester, a carboxylic acid group-containing polyester polyol is obtained, which can be used as a polyol.

In order to neutralize the carboxylic acid group, sulfonic acid group, or carboxylic acid group and sulfonic acid group in polyurethane, organic amines such as ammonia and triethylamine, alkanolamines such as monoethanolamine; pyridine, morpholine, Na, K, Among metal bases such as Li and Ca, at least one is selected as a neutralizing agent.

When preparing the aqueous polyurethane dispersion in the present invention, considering the formation of microparticles during emulsification and the fact that there is no residual solvent in the aqueous polyurethane dispersion after desolventization, it is desirable to use an organic solvent with a boiling point lower than 130°C. Its representatives are: benzene, toluene, ethyl acetate, acetone, methyl ethyl ketone, diethyl ether, tetrahydrofuran, methyl acetate, acetonitrile, chloroform, methylene chloride, carbon tetrachloride, 1,2-dichloroethane, 1,2 , 2-tridichloroethane, tetrachloroethylene, etc., they can be used alone or in combination. Among them, acetone, methyl ethyl ketone, ethyl acetate, toluene, etc. are preferably used alone or in combination as solvents with high polyurethane solubility. In addition, solvents such as N-methylpyrrolidone, ethyl glycol ether, n-butyl glycol ether, propylene glycol methyl ether and the like are used as film-forming aids, and the amount thereof is less than 50% by weight of the solid content of the resin.

When preparing the polyurethane aqueous dispersion, it is necessary to use a urethanization catalyst, and the typical representatives of the urethanization catalyst are: nitrogen-containing compounds such as triethylamine, triethylenediamine, or N-methylmorpholine; acetic acid Metal salts such as potassium, zinc stearate, and tin octoate; organometallic compounds such as dibutyltin laurate.

The water-based polyurethane adhesive of the present invention can also use plasticizers, thickeners, tackifiers, defoamers, antioxidants, ultraviolet absorbers, flame retardants, preservatives, etc. without affecting the viscosity. .

Detailed ways

Example 1 100g PBA (1,4-butylene adipate), 6.70g DMPA (dimethylol propionic acid) is added in the 500ml there-necked flask equipped with airway, stirrer and thermometer, heated and melted, Vacuum dehydration at 110-120°C, 5mmHg for 1 hour, blowing _N2 gas, cooling to about 60°C, adding about 0.05g of DBTDL (dibutyltin dilaurate) catalyst, 22.1g of HDI (hexamethylene base diisocyanate), keep warm at 75°C for 2 hours to obtain a translucent viscous liquid, cool it slightly, replace the gas guide device with a reflux device, add about 70ml of acetone, cool to 50°C, add 2.2gl, 3-butane Alcohol, heated to reflux, reacted at about 62°C for 2 hours to obtain a yellowish transparent viscous liquid, cooled to below 50°C, added the prepared triethylamine aqueous solution, stirred vigorously for about 30 minutes, heated and evaporated acetone in a vacuum to obtain white lotion. Solid content (%): 47; Organic volatile matter (%): 0-10; PH: 7; Peeling test: 9kg material is destroyed.

The steps of Example 2 are the same as Example 1. After adding acetone, add 2gl, 3-butanediol, 0.2g trimethanol propane under vigorous stirring, reflux for 2.5 hours, cool, add triethylamine solution, stir evenly, add 1.00g white Carbon black, heated to 50°C to remove acetone in vacuum. The maximum tensile force is 16kg and the material is destroyed.

The procedure of example 3 is the same as that of example 2, the reflux reaction time is 3 hours, and 2.00 g of white carbon black is added. The maximum tensile force is 19kg and the material is destroyed.

Example 4 steps are the same as Example 2, add 2.60g of white carbon black. The maximum tensile force is 20kg and the material is destroyed.

The steps of Example 5 are the same as Example 2, and the chain extender 1,3-butanediol is replaced by 2.5 g of neopentyl glycol. The maximum tensile force is 16kg and the material is destroyed.

Example 6 steps are the same as Example 1, PBA90g, DMPA7.00g, castor oil 10g, vacuum dehydration, add about 0.05g of DBTDL, TDI24.56g, react for 2 hours, add 4.5ml of triethylamine and 150ml of water to mix the solution obtained by emulsification. The peel strength of the leather material is tested, and the maximum reading of the tension meter is 11kg.

The procedure of Example 7 is the same as Example 1. After adding acetone, add 1.1gl, 3-butanediol and 1.1g of 1,3-butanediol under vigorous stirring, reflux for 2.5 hours, cool, add triethylamine solution, stir evenly, Heated to 50°C to remove acetone in vacuum. The PU leather material is tested for peel strength. The maximum reading of the tension meter is 13kg, and the material is destroyed.

Claims (11)

1. A water-based polyurethane adhesive, which is prepared as follows: The mixture of polyester polyol and hydrophilic monomer is heated to 100-120°C, after vacuum dehydration, it is cooled to 60°C by passing through N ₂ , and reacted at 50-90°C for 1-3 hours by adding diisocyanate and tin catalyst to prepare Polyurethane prepolymer containing hydrophilic isocyanate end group, add organic solvent and small molecule chain extender to carry out chain extension reaction at 50-90°C for 1-10 hours, cool to 40-50°C, add alkali under vigorous stirring The aqueous solution is neutralized and dispersed, and finally the solvent is removed in vacuum to obtain a water-based polyurethane dispersion. 2. water-based polyurethane adhesive as claimed in claim 1, it is characterized in that the polyester polyol of the polyurethane prepolymer that prepares the isocyanate terminal group that contains hydrophilic group can be by polyadipate-1,4-butylene glycol, polyadipate Ethylene Adipate, Polyethylene Adipate-Propylene Glycol, Polyethylene Adipate-Diethylene Glycol, Polyethylene Adipate-Diethylene Glycol, Polyethylene Adipate- One or two of 1,4-butanediol is optional. 3. water-based polyurethane adhesive as claimed in claim 1, it is characterized in that the diisocyanate of the polyurethane prepolymer that prepares the isocyanate end group that contains hydrophilic group can be by toluene diisocyanate, 1,4-tetramethylene diisocyanate, 1 , 6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- or 1,4-diisocyanate, isophorone diisocyanate, diphenylmethane 4 , 4-diisocyanate, dicyclohexylmethane diisocyanate, 1,6-hexamethylene diisocyanate, xylylene diisocyanate, naphthalene-1,5-diisocyanate, methylcyclohexyl diisocyanate, tetramethyl xylylene diisocyanate One or two of methyl diisocyanates are optional. 4. water-based polyurethane adhesive as claimed in claim 1, is characterized in that the hydrophilic monomer of the polyurethane prepolymer that prepares the isocyanate terminal group that contains hydrophilic group can be by 2,2 '-dimethylol propionic acid, 2, 2`-dimethylolbutanoic acid, 2,2`-dimethylolpentanoic acid, 2,2`-dimethylol octanoic acid, any one or both. 5. The water-based polyurethane adhesive as claimed in claim 1, wherein the reaction temperature for generating the polyurethane prepolymer containing a hydrophilic isocyanate end group is 70-80°C. 6. water-based polyurethane adhesive as claimed in claim 1, is characterized in that the temperature of chain extension reaction is 60-70 ℃. 7. water-based polyurethane adhesive as claimed in claim 1, is characterized in that the time of chain extension reaction is 2-3 hour. 8. The water-based polyurethane adhesive as claimed in claim 1, wherein the organic solvent is acetone, butanone, N-methylpyrrolidone, ethyl acetate, dimethylformamide or mixtures. 9. water-based polyurethane adhesive as claimed in claim 1, is characterized in that small molecule chain extender is ethylene glycol, butanediol, hexanediol, diethylene glycol, neopentyl glycol, trimethylol propane, One or a mixture of ethylenediamine, melamine, 1,4-butanediamine, and propylenediamine. 10. water-based polyurethane adhesive as claimed in claim 1, is characterized in that alkaline substance is NaOH, KOH, triethylamine, trimethylamine in alkaline aqueous solution. 11. water-based polyurethane adhesive as claimed in claim 1, is characterized in that tin catalyst is dibutyltin dilaurate, stannous octoate.